According to these links, Yotaphone 3+ has almost the same hardware as Yotaphone 3, but it can freely screen any app on the Eink screen instead of forcing you to use their build-in apps like Yotaphone 3. The Android version is 8.1 Oreo.

What's surprising to me is that the Yotaphone 2 could install Google apps and mirror the screen to the e-ink screen.

Fact: Amazon owns (or did a few months ago when I last checked) the patent for this technology.
My theory: this prevented Yota from selling the Yotaphone 3 worldwide. So while developing the Yota 3, they started discussions with Amazon. In the meantime they started selling the crippled Yota 3 in China, to generate some cash flow and keep the competition (Hisense A2) from taking their market. They must have reached an agreement with Amazon recently, so they are releasing their full-function model worldwide.

That did not prevent them from selling YotaPhone 2.
YotaPhone 2 came with 4.something version of Android and I have upgraded it to 5.0
There is also update to 6.0 available for Russian version (that can be installed, after some finagling, to the Chinese and International one) but I am not interested in installing that.
YotaPhone 2 has Google Play and has the "mirror the screen to the back" functionality.

"What's surprising to me is that the Yotaphone 2 could install Google apps and mirror the screen to the e-ink screen. Fact: Amazon owns (or did a few months ago when I last checked) the patent for this technology"

Now, that is interesting.

I was looking at the first reviews of the Lenovo Yoga Book c930 and found a notice by someone mentioning that "it didn't have Drag & Drop from screen to screen" and asked myself why this has not really been implemented anywhere since the browser that came with the enTourage eDGe. That at least could take a website shown on the LCD-side and transfer it to PDF or epub on the eInk-display.

Waiting4something, what you talk about is not exactly a hack. You have to enter a code in the phone and you enter in a developer menu where you can make the mirror possi le. On the forum of XDA there is explained a way to do it in just one or two clicks.

Anyway, for those who doesnt have the yotaphone yet, just need to wait until the new version will be released and it seems everything is going to be easy. Lets see....

I'm tempted to get the original yotaphone 3 though. It's already a reasonable price, and the new one will be expensive. How long until the price comes down I don't know; also, would the original lose its value as a result? (Therefore even more attractive financially). I suppose not.